Found this the other day from my old computer. It is for a 2000 Maxum 1900, but I thought I might post it in case it could help someone with a similar setup. I'd also appreciate feedback in case anything is missing so I have a more updated list for my next boat. Of course, not all boats are the same:

BOAT WINTERIZING CHECKLIST:

1. TREAT GAS: Put StaBil in fuel tank, either before refilling, or before trailering or using the boat.
2. CHANGE ENGINE OIL: Run engine on muffs or with the boat on the water (preferably) for about 10 minutes minimum (do not run too long on muffs) to heat up oil. Oil will get hotter if you run on the water, and will stay hot for over an hour.
3. Pump out old oil, spin off old oil filter, and install new oil filter. Fill with fresh oil.
4. FOG ENGINE: Spin off old fuel filter and drain out gas. Fill old fuel filter with a 50/50 mix of 2-cycle oil and gas, or 50/50 mix of 2-cycle and fuel injector cleaner. Spin on old filter, being sure not to spill any mixture in bilge.
5. Run engine on muffs at medium idle (about 1000rpm) until it stalls. If it almost stalls, but then returns to normal idle, you have used up all the fogging mixture, and will need to re-do step 4. Run at a lower idle and/or use more 2-cycle oil if this happens. The engine MUST stall for this to work. (This step will also coat everything with fresh oil from step 3).
6. As an optional step, you can remove the spark plugs and spray fogging oil in each cylinder. This is usually not necessary, is very difficult (requires a mirror to see what you’re doing, and knuckle attachments to get the plugs out), and isn’t required by Mercruiser.
7. Remove old fuel filter and install new one.
8. DRAIN BLOCK: This is the most important step!!!! Unscrew all 6 blue plastic plugs on the engine. There will be 1 on either exhaust riser, 1 on each side of the block, one on the power steering cooler on the port side bottom, and 1 on the water pump. Use a coat hanger or wire to clear any blockages. Reinstall blue plugs finger tight, making sure black O-rings are on.
9. Remove Thermostat housing and pour antifreeze in opening (you may want to remove hoses). Cleam off old gasket material and reinstall new T-stat housing gasket (and Thermostat if it is old), and install T-stat housing. Use new lock washers, and torque to 30 ft. lbs. Make sure there is no water in the screw holes. Don’t forget to install U-shaped engine lift ring.
10. DRAIN/REFILL DRIVE: unscrew screw at base of drive on “bullet”. Catch old oil in pan. Unscrew screw at top of drive on port side. Remove any metal filings from screws (they are magnetic)
11. After all oil has drained, install drive oil pump in bottom hole, and begin pumping in new oil. OIL MUST BE PUMPED IN FROM BOTTOM!! When oil begins to come out upper hole, install upper screw with new washer and continue pumping until reservoir is full.
12. Remove drive oil pump from lower hole, and quickly install screw with new gasket.
13. Do not run engine unless you want to re-fog, but be sure to keep an eye on fluid levels next season, and top off as necessary.
14. LUBE GREASE POINTS: Pump grease in all zerks, including drive coupler (VERY hard to reach).
15. OIL ENGINE: Spray fogging oil, CRC or engine oil on engine and linkages. Spray any metal parts with CRC (snaps, wiring harnesses, fishing gear, etc)
16. Remove battery and store properly. Charge about once a month thru the winter.
17. CLEAN BOAT: Wash and wax boat. Remove carpeting and any items that could hold moisture, set cushions ajar to promote air circulation. Place dryer sheets about boat to discourage mice. Remove any items that could be damaged by cold. Remove all battery powered devices (cell phones, VHF, etc).
18. Cover boat and secure straps.
19. WINTERIZE TRAILER: top off tires with air, grease bearings (inspect and repack if you want…not required with Bearing Buddys). Spray any rusty areas with instant galvanizer, spray electrical connections with CRC, change out brake fluid, cover actuator with garbage bag or canvas to keep water out of reservoir. Spray tire dressing on all tires. Optionally, jack up trailer to get weight off springs and tires.
20. Have a beer 

PP:
That is quite a list. I know that the mechanics at our mountain lake use much the same processes you have identified. But, that is one reason that I do not trust what they do. I know, I get comments like "We've always done it this way and have never had problems." They can probably say that because of a multitude of reasons, but problems they may cause may not appear for a long time.

Therefor, I believe it is proper to say that as engine/mechanical technology continues to be more technical, generic actions that used to be good across the board may not be correct for newer models, even within a particular manufacturer's product line. For example, VP uses a much different method to fog the engine on my 2012 engine. This may because it has multi-port fuel injection or maybe because it has catalytic converters.

Therefore, If one were to use a check list, it might prudent to create his own list, but use only the main topics you have included. Then, fill in the details for each topic by including the exact procedures for that boat/motor as they are included in the owner's manual. Check list--excellent idea!

Yes, my intent was to offer one type of procedure, and have others tailor it to their particular engine and vessel. I'll add the disclaimer PLEASE CHECK WITH YOUR MANUFACTURER on exact procedures for your make and model. Even if one has a mechanic or the marina winterize, it's always good to check their work. I live by the motto "trust, but verify".

Offhand, I had the Merc 4.3 TBI with Alpha 1 Gen 2. And it's been a while since I had that boat, so I'm sure things have changed. Hopefully, that will change soon too. We're immersed in looking at late season offerings in pre owned cruisers.

Yea, that list is too long for me to read

Many folks, after doing a few winterizations come up with their own twists to a common theme. The whole idea is to prevent freeze damage and provide extra lubrication to engine components.

I have full closed cooling systems, sea water strainers and MPI engines, so my procedure is rather unique.

I think just about everyone's process includes #20

A very good list, it is long to read eh Ted?
One thing I'd add for people with outdrive boats, is that the drive should be removed each season so you can check for water in the driveshaft bellows and grease the gimble bearing, u joints and driveshaft splines (some newer boats have permenantly lubed gimbles and u joints). This one job will help you avoid expensive repairs due to water in the bellows. I think a lot of people and mechanics skip this till there is a problem....

And, while in storage, always keep the drive down to reduce stress on the bellows. At least that is what I have heard and follow religiously. On a lift, you may need to leave it a bit elevated to keep the skeg out of the water--maybe that isn't really necessary, but.......

That is true, I made the one on my Cobra last 11 seasons here in salt water land by keeping the drive down.

Good point about the bellows. I used to keep mine down except for trailering. Never removed the drive, as the final and splines could be greased through zerks no but I knew so.e guys who removed the lower unit for security

"no but I knew so.e guys who removed the lower unit for security"

??

Can't steal what isn't there.

Thanks Kevin. Is that some kind of secret code or something? (:-)

No secret code was just agreeing with the poster who commented on people taking off the lower units in the winter for security purposes - Can't steel what isn't there.

We actually did the "w" thing this weekend. Really wanted to get one more outing in but looking at the calendar it wasn't looking likely.

End of a great summer. Most boating we have done in a long time.

I pull the outdrives, because they should have the u-joints greased, and you can also check the gimbal bearing to see if it is OK. Theft is an issue in unattended storage areas, so folks pull their outdrive as anti-theft.

I had my boat pulled out for the season yesterday, so now I am at it doing the big "W" thing . . .

For salt water folks, I added a step this year, based on some cooling system work that I did last year . . . where I found a pretty significant calcium build up in the heat exchangers, reducing their effectiveness. So, this year, I mixed up about 3 gallons of "Salt-Away" solution and sucked it into the cooling system (sea water side) and then let it sit for a few hours. Then I ran regular water to flush out the salt-away.

I'm not going to open up the heat exchanger to see if the Salt-Away worked, at least not right now, but if the cooling system keeps working, then I'll keep using Salt-Away as part of my winterization routine.

Another thing about freeze protection that I did this year was to check the strength (i.e. freeze point) of the coolant in my closed cooling system. The port engine was fine and the tester indicated about a -45 F freeze point. The starboard engine was a bit iffy at -10 F. So, I added some more pure AF to the starboard engine. Got to re-check it after I run it for a while.

Overall, I do like closed cooling . . . Soooo much better than open cooling, particularly for ocean boating.

Ted, if the salt away did not do the job, try Barnacle Buster or RydLyme. I used Barnacle Buster on my heat exchangers this year and was happy with the results.

The salt-away did seem to do a good job on the heat exchangers. I ran the engines up to temperature before the salt-away and got 172 F on the Stbd engine and 169 F on the port engine. after doing the salt-away treatment, I ran the engines again under the same conditions as my pre-treatment run and got 3 degrees F lower operating temperature on each engine . . . 172/169 (before) and 169/166 (after)

So, I'll make it an added step to my winterization process.

We are pulling the Grady-White 305 out on Saturday. Just reading through the Yamaha Service manual (the boat has twin 350's) . They recommend completely emptying the fuel tank. First time that I have seen that as a recommended procedure.

Last weekend the weather was low 70's and absolutely beautiful, this weekend upper 60's on Saturday and 2" of rain forecasted for Sunday. Glad I winterized last week.

We are in the 40's in Chicago this weekend. Would love the 60's

I no longer put antifreeze in engine. With the polar vortex in past winters, I can get close to the antifreeze freeze point. Just drain the water ensuring dirt isn’t blocking the drainage (clothes hanger is a must ). Leave drain plugs off until spring.

Yes, the rating on the antifreeze is for pipe bursting, which is not sufficient protection of some of the plastic parts that some of the cooling systems have. The -50 F stuff gets pretty solid at about -20-25 F . . . well within the range of a polar vortex

So, you are wise to drain or use the -75 or -100 F stuff.